1. Cellular Respiration Biology 11 A. Allen http://fusionanomaly.net/mitochondria.html 1

2. Cellular Respiration Cellular respiration is… The process by which a cell breaks down sugar or other organic compounds to release energy used for cellular work; may be anaerobic or aerobic, depending on the availability of oxygen. Aerobic respiration can be summarized by the following formula: C 6 H 12 O 6 + 6O 2  6H 2 0 + 6CO 2 + energy (36 ATP) 2

3. Glycolysis Glycolysis is the first stage of cellular respiration. Glycolysis has two parts; Glycolysis I & Glycolysis II. In order to ‘kick-start’ glycolysis I, activation energy is required (ATP). Sugar is split into two PGAL’s. In glycolysis II, PGAL is oxidized and ATP is produced. The overall pathway gets its name from this sugar splitting (glyco = sugar, lysis = split). Glycolysis occurs in the cytosol (The fluid portion of the cytoplasm, outside the organelles ). 3

4. An overview of Aerobic Cellular Respiration Can you find Glycolysis? 4

5. Glycolysis I Glucose 6-C Glucose ~P “glucose-6-phosphate” 6-C, 1 Phosphate ATP ADP P~ Fructose ~P “Fructose 1,6-bisphosphate” 6-C, 2 Phosphates ATP ADP X2 PGAL AKA G3P (3-C, 1 phosphate) Glycolysis I is a series of endergonic reactions 1.Glucose enters the cell by diffusion 2.ATP donates a phosphate to the substrate. (1 ATP used) Glucose-6-phosphate is produced. 3.Glucose-6-phosphate is rearranged to fructose-6-phosphate (another 6-C sugar) 4.another ATP donates its phosphate (1 ATP used). Fructose 1,6-bisphosphate is produced. 5.The fructose 1,6 bisphosphate molecule is split into 2 PGALs (phosphoglyceraldehyde), a 3-carbon compound. Note PGAL is also known as glyceraldehyde 3-phosphate (G3P) **Glycolysis I …** 2 ATP (2 ATP’s are used.) PGAL AKA G3P Animation 1 2 3 4 5 Fructose~P “fructose-6-phosphate” 6-C, 1 Phosphate 5

6. Glycolysis II X2 PGAL (G3P) (3-C, 1 phosphate) Pyruvate (Pyruvic Acid) (3-C, 0 phosphates) PiNAD + NADH In Glycolysis II, each PGAL (2 from 1 molecule of glucose) is oxidized to release energy. This process is exergonic. 1. PGAL is oxidized. NAD takes electrons (NADH is formed). The oxidized PGAL then accepts a Pi from the cytosol. 1,3 bisphosphoglyerate (BPG) is formed 2. ADP is phosphorylated to ATP (x2) as it removes the phosphate from the substrate. 3-phosphoglycerate (PGA) is formed. (substrate level phosphorylation: when ADP removes Pi from the substrate to form ATP) 3. 3-phosphoglycerate is rearranged to 2- phosphoglycerate which is then rearranged to phosphoenolpyruvate (PEP). Water is given off in this process. 4. PEP gives a phosphate to ADP to make ATP. Pyruvate (AKA Pyruvic acid) is formed. ADP ATP **Glycolysis results in a net gain of …** 2 ATP (2 ATP’s are used and 4 are produced) 2 NADH These hydrogens are transported to the mitochondria for more ATP production Animation 1 3 4 1,3 bisphosphoglycerate (BPG) (3-C, 2 phosphates) 2 ATP ADP 3-phosphoglycerate (PGA) (3-C, 1 phosphate) 2-phosphoglycerate (3-C, 1 phosphate) phosphoenolpyruvate (PEP) H 2 O 6

7. Substrate Level Phosphorylation The direct phosphate transfer of phosphate from an organic molecule to ADP. IMPORTANT! 7

8. Think Together! Partners `A` and `B` take turns answering the questions below. A.What is the basic difference between Glycolysis I and Glycolysis II? B.What is the role of NAD? A.Using your notes, describe glycolysis to your partner using the terms reduce, oxidize & phosporylation B.How is substrate-level phosphorylation involved in glycolysis? Where? 8

9. Coenzyme A substance that enhances or is necessary for the action of enzymes. They are generally much smaller than enzymes themselves. NAD is a coenzyme that serves and an electron carrier. 9

10. Vocabulary GAME! Glucose fructose PGAL Pyruvate phosphate Glucose-6 phosphate NADH ADP endergonic 10

11. Circle the end products of glycolysis. Where do they go next? 11

12. Pyruvate Oxidation (Pyruvic Acid Oxidation) Remember, in glycolysis, glucose was oxidized to 2 pyruvate molecules. Therefore, the above biochemical pathways run twice for every molecule of glucose! Pyruvate Oxidation ONLY HAPPENS IF O 2 is present! Pyruvate (pyruvic acid) (3-C) NAD + NADHCO 2 Acetate (Acetic acid ) (2-C) Coenzyme A (or ‘CoA’) acetyl coenzyme A (or ‘acetyl coA’) X2 1 2 2.Acetic acid combines with coenzyme A to form acetyl coenzyme A. 1.The two pyruvate from glycolysis diffuse into the mitochondrion’s matrix. Here, it is oxidized by NAD + (which is reduced to NADH) to make acetate, a 2-carbon compound. (The carbon is lost in the form of CO 2 ) Animation **Pyruvate Oxidation results in a net gain of …** 2 NADH. These hydrogens are transported to the Electron Transport Chain for more ATP production 12

13. Stop & Think! Under what conditions would the rate of pyruvate oxidation in the muscle cells of an athlete slow down? 13

14. Can you find Pyruvate oxidation? Where does it occur? 14

15. Krebs Cycle 1.Acetyl coenzyme A enters the Krebs cycle and combines with Oxaloacetate (4-C), to make citrate (6-C). Coenzyme A is recycled for further use. 2.Citrate is rearranged to isocitrate (6-C) 3.NAD accepts hydrogens from isocitrate which is therefore oxidized. One molecule of CO 2 is given off as isocitrate loses one carbon. α-ketoglutarate (5-C) is formed. 4.α -ketoglutarate (5-C) is oxidized to succinyl Co-A (4-C). A CO 2 is removed, coenzyme A is added, and 2 hydrogen atoms reduced NAD to NADH. Succinyl C0-A is produced. 5.Succinyl Co-A (4-C) is converted to succinate (4-C). A Pi from the matrix displaces C0-A from succilyl Co-A. The phosphate is then tansfered to GDP (guanosine diphosphate) to make GTP. Then the Pi is transferred to ADP to make ATP!Citrate (6-C) α -ketoglutarate (5-C) Succinate ( 4-C ) Oxaloacetate (4-C) NAD CO 2 NAD NADH acetyl coenzyme A (or ‘acetyl coA’) 1 Coenzyme A (or ‘CoA’) NADH 3 4 X2 Animation GTP GDP + Pi ATP ADP + Pi Isocitrate (6-C) Succinyl-CoA ( 4-C ) Co-A Co-A 2 5 15

16. Krebs Cycle 6.Succinate (4-C) is oxidized to fumarate (4-C). Not enough energy is released to reduce NAD, so FAD is instead reduced to FADH 2. 7.Fumarate (4-C) is converted to malate (4-C). 8.Malate is oxidized to oxaloacetate (4-C). 2 hydrogens are reduced NAD to NADH. Oxaloacetate has been restored, so the cycle can continue! Yahoo! Only 2 ATP’s have been produced from Krebs cycle.  Citrate Citrate (6-C) α ketoglutarate α ketoglutarate (5-C) Oxaloacetate (4-C) NAD CO 2 FAD FADH 2 NAD NADH acetyl coenzyme A (or ‘acetyl coA’) 1 Coenzyme A (or ‘CoA’) NADH 3 6 7 8 Final products of Krebs Cycle per molecule of glucose: 3 x 2 = 6 NADH  (to electron transport chain to make ATP) 1 x 2 = 2 FADH2  (to electron transport chain to make ATP) 1 x 2 = 2 ATP X2 Animation NAD 4 GTPGDP + Pi ATP ADP + Pi Succinate ( ( 4-C ) NADH CO 2 Isocitrate Isocitrate (6-C) malate (4-C) fumarate (4-C) H20H20H20H20 Succinyl-CoA ( ( 4-C ) Co-A Co-A 2 5 16

17. Think Together! Why is there a “X2” on the diagram of the Krebs Cycle? Krebs cycle only yields 2 ATP per molecule of glucose, but it also results in 6 NADH and 2 FADH 2 produced. What do you think NADH and FADH 2 is for? 17

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19. Oxidative Phosphorylation (Electron Transport Chain) The electron transport chain is located on the inner membrane of the mitochondrion. It consists of several electron carriers which accept electrons from NADH and FADH 2 (from glycolysis and Krebs cycle). It requires O 2 ! Animation #1 Animation #1 Animation #2 Animation #2 19

20. …Oxidative Phosphorylation (Electron Transport Chain) [1] Energized electrons from Glycolysis and Krebs cycle are carried to the electron transport chain via NADH... [2]...and FADH 2 2 1 Animation #1 Animation #1 Animation #2 Animation #2 20

21. …Oxidative Phosphorylation (Electron Transport Chain) [3] Electrons are passed through a series of electron carriers which become reduced/oxidized as they pass off the electrons [complexes I -IV]. At different places along this chain, the energy released from the electrons is used to ‘pump’ protons (H + ) across the inner membrane of the mitochondrion into the intermembrane space [4]This creates a concentration gradient in the intermembrane space. 3 4 2 1 NADH Dehydrogenase (H + pump) Cytochrome bc 1 complex (H + pump) Cytochrome c oxidase complex (H + pump) Animation #1 Animation #1 Animation #2 Animation #2 21

22. …Oxidative Phosphorylation (Electron Transport Chain) [5] The H + ions are allowed to pass back into the matrix through ATP synthase. [6] Using the energy from the flow of protons, ADP is united with Pi to form ATP. Note that because NADH and FADH 2 enter the electron transport chain at different locations, they yield different amounts of ATP; NADH yields 3 ATP and FADH 2 yields 2 ATP. [7]The electrons unite with protons (H + ) and oxygen at the end of the ETC to form water. If insufficient O 2 is available in the cell, the ETC will not work! What happens then?...... 3 4 2 1 5 6 7 NADH Dehydrogenase (H + pump) Cytochrome bc 1 complex (H + pump) Cytochrome c oxidase complex (H + pump) Animation #1 Animation #1 Animation #2 Animation #2 22

23. Electron Transport and Chemiosmosis NADH H+H+ NAD + H+H+ H+H+ H+H+ CoQ NADH Dehydrogenase 23

24. Fig. 9.15 Electron Transport and Chemiosmosis NADH H+H+ NAD + H+H+ H+H+ H+H+ CoQ Cytochrome bc 1 complex Cyt C NADH Dehydrogenase 24

25. Fig. 9.15 Electron Transport and Chemiosmosis NADH H+H+ NAD + H+H+ H+H+ H+H+ CoQ Cytochrome c oxidase complex NADH Dehydrogenase Cytochrome bc 1 complex Cyt C 25

26. Fig. 9.15 Electron Transport and Chemiosmosis NADH H+H+ NAD + H+H+ H+H+ H+H+ 2 H + + ½ O 2 H20H20 Electron transport chainchemiosmosis CoQ NADH Dehydrogenase Cytochrome bc 1 complex Cyt C Cytochrome c oxidase complex 26

27. Electron Transport and Chemiosmosis NADH H+H+ NAD+ H+H+ H+H+ H+H+ 2 H+ + ½ O 2 H20H20 H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ ADP + P ATP 27

28. Smokin’ Chemiosmosis & Electron Transport Animations http://vcell.ndsu.nodak.edu/animations/atp gradient/movie.htmhttp://vcell.ndsu.nodak.edu/animations/atp gradient/movie.htm http://vcell.ndsu.nodak.edu/animations/etc/ movie.htmhttp://vcell.ndsu.nodak.edu/animations/etc/ movie.htm 28

29. Can you see why FADH 2 & NADH end in different ATP yields? 29

30. Cyanide Blocks the Electron Transport Chain Cyanide is a poison that inhibits cytochrome oxidase activity. Why can cyanide cause death? 30

31. Cyanide Blocks the Electron Transport Chain Cyanide is a poison that inhibits cytochrome oxidase activity, preventing oxygen from acting as the final electron acceptor in the electron transport chain. This disruption virtually shuts down ATP production resulting in coma and death. That is why cyanide is a poison. However, it is not poisonous to all organisms. Anaerobic bacteria, called MIT-13 actually live on cyanide – they use it the same way aerobes use oxygen. 31

32. Summary of Aerobic Cellular Respiration 32

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34. Structural Formula of ATP 34

35. Label the diagram 35

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37. Net Energy Yield of Aerobic Respiration ATPs NADHs FADH 2 s ATPs From ETC Total ATPs Glycolysis 2 2 0 4 6 Pyruvic Acid Oxidation 0 2 0 6 6 Krebs Cycle 2 6 2 22 24 Total 4 10 2 32 36 A BCDE FGHIJ KLMNO PQRST Huh?! 37

38. Anaerobic vs. Aerobic Respiration NOTE: What happens after glycolysis depends on whether or not oxygen is present… If O 2 is absent….If O 2 is present…. Pyruvate (Pyruvic Acid) (3-C) NADH NAD + X2 Lactate (Lactic acid) (3-C) Pyruvate Goes to the Kreb’s cycle in the mitochondria (aerobic respiration) for complete oxidation. This process is called … lactate (lactic acid) fermentation Lactic acid (animals) Once thought to make muscles fatigued after Strenuous exercise) 38

39. Think Together! With your partner, discuss: Does lactic acid fermentation yield any energy? Assume the energy demands within a cell greatly exceeds the body’s ability to deliver oxygen. What is the point of pyruvic acid being converted to lactic acid? HINT: NAD is a limited commodity in the cell. 39

40. Alcoholic Fermentation (in yeast) An anaerobic step that yeast use after glycolysis that breaks down pyruvate to ethanol (aka ethyl alcohol) and carbon dioxide. Pyruvate (Pyruvic Acid) (3-C) NADH NAD + X2 Ethanol (the alcohol found in beer, wine, etc.) (2-C) Acetaldehyde (2-C) C0 2 40

41. Alternate Pathways Carbohydrates are your body’s nutrient of choice. Proteins lipids and nucleic acids can also be used. 41

42. Protein Catabolism Proteins are made of different types of amino acids. The amino groups of amino acids are removed (deamination). What remains of the amino acids tar ether converted to various components of glycolysis or Krebs i.e pyruvate, acetyl CoA, alpha ketoglutarate. You know the rest! 42

43. Lipid Catabolism Triglycerides are made of glycerol and fatty acids. Your digestive system breaks triglycerides into these components. Glycerol may be converted into glucose via gluconeogenesis or to DHAP (what’s next…?) The fatty acids enter the matrix and undergo beta oxidation (acetyl groups are removed from the fatty acids and combine with CoA to form Acetyl CoA… 43

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45. References http://cwx.prenhall.com/bookbind/pubbooks/mcmurrygob/medialib/media_portfolio/21.html http://members.aol.com/BearFlag45/Biology1A/LectureNotes/lec10.html Nelson Biology 12 45